Bow is in the East End of London, north of Isle of Dogs (Canary Wharf area). I'm not sure about rent, but it is cheaper than West and North London, but due to the emergence of the Docklands, the prices maybe going higher. I don't know if there is much nightlife in this area, most things are in central London, though getting to central London from Bow should not be an issue (tube, DLR).
bvamin